Transmission for well-drilling machinery



March 11, 1952 c. M. OLEARY TRANSMISSION FOR WELL-DRILLING MACHINERY 6Sheets-Sheet 1 Filed Feb. 15, 1946 March 11, 1952 c. M. OLEARYTRANSMISSION FOR WELL-DRILLING MACHINERY 6 Sheets-Sheet 2 Filed Feb. 15,1946 INVENTOR. 6%42112: Mdz fg.

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C. M. O'LEARY TRANSMISSION FOR WELL March 11, 1952 DRILI..ING MACHINERY6 Sheets-Sheet 3 Filed Feb. 15, 1946 (Z 12 Ma 64 March 11, 1952 c. M.OLEARY 2,589,119

TRANSMISSION FOR WELL-DRILLING MACHINERY Filed Feb. 15, 1946 I 6Sheets-Sheet 4 Eff March 11, 1952 c, M, OLEARY TRANSMISSION FORWELL-DRILLING MACHINERY 6 Sheefcs-Sheet 5 Filed Feb. 15, 1946 Z ma m 7 M@i 7mm 0 March 11, 1952 c O'LEARY 2,589,119

TRANSMISSION FOR WELL-DRILLING MACHINERY Filed Feb. 15, 1946 6Sheets-Sheet 6 l/ M5 E Z2 2! 7/7 Z44 INVENTOR..

[arlei BY Patented Mar. 11, 1952 UNITED STATES PATENT OFFICETRANSMISSION FOR WELL-DRILLING MACHINERY 13 Claims. 1

The present invention relates to an automatic multiple speedtransmission mechanism and to a rotary well drilling machine employing aspecial form of said transmission.

It is one object of the present invention to provide an improvedautomatic multiple speed transmission.

Another object is to provide, in combination with a hydrokinetic torqueconverter, an automatic multiple speed ratio transmission which willmaintain the speed ratio of the converter within a predeterminedefiicient range regardless of variations in the load.

Another object of the invention is to provide a combination of the typementioned in which the transmission will also maintain the speed ratioof the converter within predetermined limits regardless of variations inthe input speed of the converter.

Another object of the invention is to provide a mechanism for actuatinga control instrumentality in response to the existence of apredetermined ratio between the speeds of two shafts.

Another object of the invention is to provide means by which thetransmission may be selectively subject to automatic or manual control.

Another object of the invention is to provide an improved multiple speedtransmission having a plurality .of power take-offs and means to driveeach take-off in either direction at several speed ratios.

Another object of the invention is to provide a transmission of the typelast mentioned in combination with two independent power sources, whichtransmission is adapted selectively to drive one or more power take-offsfrom either one or both power sources or to drive two take-offssimultaneously at several speed ratios from separate power sourcesrespectively.

A further object is to provide an improved control mechanism forsynchronizing a plurality of internal combustion engines.

Another object of the invention is to provide an improved rotary welldrilling machine characterized by its compactness, high efiiciency,flexibility and ease of operation.

Other objects and advantages of the invention will become apparent fromthe following specification, the accompanying drawings and the appendedclaims.

Referring to the drawings in which like numerals are applied to likeparts in the several views:

Figure 1 is a diagrammatic plan view of a well drilling machineincorporating all of the features of the presentinvention;

Figure 2 is a longitudinal section taken on the line 22 of Figure 1showing the actual construction of one of the planetary transmissionunits indicated diagrammatically in Figure 1;

Figure 3 is a transverse section taken on the line 3-3 of Figure 2;

Figure 4 is a transverse section taken on the line 4-4 of Figure 1;

Figure 5 is a longitudinal section taken on the line 55 of Figure 1;

Figure 6 is a fragmentary section taken on the line 6-43 of Figure 1showing the engine synchronizing mechanism in the engine throttlecontrol linkage;

Figure 7 is a plan view of the mechanism shown in Figure 6;

Figure 8 is a transverse section taken on the line 88 of Figure 1;

Figure 9 is an elevation view of the throttle control lever mechanismwith the surrounding casing in section;

Figure 10 is a transverse section taken on the line 10-) of Figure 9;

Figure 11 is a plan view of the differentially operated switchesemployed to control the speed ratios in the transmission mechanism ofFigure 1;

Figure 12 is a view of one of the difierentially operated switches takenpartly in section on the line l2|2 of Figure 11;

Figure 13 is a horizontal section taken on the line 13-43 of Figure 12;

Figure 14 is an enlarged view of a portion of the mechanism shown inFigure 11;

Fig. 15 is a diagrammatic view of the combined electrical controlcircuit for the transmission;

Fig. 16 is a longitudinal, sectional view taken through the controlmechanism for the manually operated switches in the circuit of Figure15;

Figure 17 is a transverse section taken on the line Il-l'l of Figure 16;

Figure 18 is a transverse section taken on the line 18-48 of Figure 16;

Figure 19 is a transverse section taken on the line I9l9 of Figure 16;

Figure 20 is a transverse section taken on the line 20-40 of Figure 16;

Figure 21 shows the representative torque and efficiency curve of thetorque converters employed in the mechanism of Figure 1;

Figure 22 is a diagrammatic view of a modified form'iof the inventionwith a fragmentary, longitudinal section through a simplified form oftransmission shifting control switch;

Figure 23 is a view taken on the line 2323 of Figure 20; and

Figure 24 is a fragmentary view partly diagrammatic of a modified formof transmission unit.

In general, the complete machine of the present invention embodies, as asingle unit, a plurality of engines connected by hydrokinetic torqueconverters to an improved form of multiple speed transmission whichincorporates power take-offs for driving the hoisting drum, the rotarytable and the slush pumps of a rotary well drilling machine. Thus, asshown in Figure 1, the mechanism includes a base I having mountedthereon a pair of internal combustion engines 2 and 3. The shaft ofengine 2 is connected in any suitable manner to the input shaft 4 of ahydrokinetic torque converter 5 having an output shaft 6 connected bybevel gearing to a shaft 1 of the transmission mechanism. The shaft ofengine 3 is similarly connected to the input shaft 8 of a hydrokinetictorque converter 3 whose output shaft 13 is connected by bevel gearing li to a transmission shaft l2 that is coaxial with the previouslymentioned shaft 7 and which may be connected to shaft 1 at the will ofthe operator in any desired manner as by a pneumatically operatedclutch, indicated diagrammatically at I3.

The opposite end of shaft constitutes the input shaft of a two speedtransmission :4 having an output shaft l5 which is coaxial with theshaft 1. As best shown in Figure 2, the transmission l4 is'of aplanetary type and is carried by the adjoining ends of the shafts l andI5. Thus, the right-hand end of shaft 1, as viewed in Figures 1 and 2,is journaled in a bearing it carried by a web or pedestal l1 formedwithin the casing of the transmission, while the lefthand end of shaft15 is similarly journaled in a bearing 18 carried by a web or pedestalE3. A planetary cage 20 is journaled by means of bearings 2| and 22 onthe ends of the shafts i and i5 respectively. A plurality of gearclusters 23 which are fixed on shafts 24, respectively, are journaled inthe cage 20. Each of the gear clusters comprises a pair of gears whichmesh respectively with gears 25 and 26 carried respectively by the endsof the shafts "l and 15. It will be noted that gear 25 is smaller thanthe planet gears with which it engages, while the other planet gears ofeach cluster are smaller than the gear 26. Consequently, when the planetcage 20 is held stationary, the shaft 15 will rotate at a lower speedthan shaft l, but in the same direction. The ends of the shafts i and I5are provided with axial bores which receive a pilot shaft 21 whichassists in holding the ends of the shafts in proper alignment; and thepilot shaft 21 is provided with a central bore which may be used tosupply lubricant to the mechanism.

The ends of the shafts24 of the planetary gear clusters are extended andeach is provided with a cone friction brake element 28 adapted tocooperate with a mating cone friction brake 29 carried by a brake plate30. The plate 30 is slidably mounted on the shaft 1 and adapted to beforced to the right, as viewed in Figure 2, to cause engagement of thebrakes. This function is performed by means of an annular movablecylinder 3| which co-operates with an annular piston 32 fixed to thebearing pedestal l'l. The piston 32 is provided with a passageway 33which communicates with a pipe 34 through which air under pressure maybe supplied in the manner hereinafter described to actuate the annularcylinder 3| and thereby cause engagement of the planet brakes. Ifdesired, suitable springs, not shown, may be employed between brakeplate 30 and cage 20 in the regions intermediate brakes 23 to effectdisengagement of the brakes when the air pressure is relieved.

When the brakes 28 are held against rotation about their own axes by thebrake elements 29, the shafts l and I5 are locked together in a 1 to 1ratio. When the brake elements are disengaged, the planetary gearingtends to rotate shaft l5 in the same direction as shaft 1 and at thesame time tends to effect a reverse rotation of the planet cage 20. Inorder to prevent such reverse rotation of the planet cage, a pluralityof equally spaced one way brake blocks 35 are mounted in suitablerecesses formed in the casing of the transmission, as best shown inFigure 3. These blocks are so constructed and arranged that they operateto prevent counterclockwise rotation of the planet cage 20, as viewed inFigure 3. Accordingly, when the brakes 28 are disengaged, the planetarycage 20 will be held stationary by the blocks 35 and shaft l5 will bedriven by shaft 1 in the same direction as the latter but at a reducedspeed. This form of two speed transmission is peculiarly suited for usein heavy hoisting operations for the reason that shifts in the speedratio may be effected at any time under load without danger of droppingthe load. If for any reason the air supply for shifting the transmissionfails, the transmission will remain in its low speed ratio by reason ofthe one way brake blocks 35.

The output shaft [5 of transmission 14 carries a multiple rope or V-beltpulley 36 which is employed as the power take-off to operate the slushpumps, not shown. A clutch of any desired construction should beprovided between the shaft l 5 and the slush pumps at any point in thedrive connection in order to disengage the slush pumps when the drillingoperation is interrupted.

A sprocket 31 is normally freely rotatable upon the shaft l5 but may beclutched to the shaft I5 at any time by means of an air operated clutch,indicated diagrammatically at 38. The sprocket 3'! is connected by achain 39 to a similar sprocket 45 fixed on a shaft 4| which is parallelto the shafts 7, l2 and I5 and mounted within the same casing. Shaft 4|has freely rotatable thereon a sleeve 42 which may be clutched to theshaft 4| at any time by means of an air operated clutch, indicateddiagrammatically at 43. Sleeve 42 carries a gear 44 which meshes withand. drives a gear 45 on a parallel countershaft 46. A sprocket 4'! onshaft 46 is connected by a chain 48 to the drive sprocket 49 of therotary table 50. The rotary table and its internal drive mechanism maybe conventional or of any desired construction.

Shaft 4| also constitutes the input shaft of a two speed planetarytransmission, indicated diagrammatically at 5| in Figure 1 and shown ingreater detail in Figure 5. The transmission 5! is identical inconstruction and mode of operation to the transmission I 4 previouslydescribed except that a different form of shifting mechanism isemployed, as hereinafter pointed out in greater detail. The output shaft52 of the transmission 5i constitutes the input shaft of a thirdtwospeed transmission 53, which is likewise identical in constructionand mode of operation to the transmission 14 except for its shiftingmechanism. However, transmission 53 is preferably reversed in positionso that it will establish either a 1 to l drive ratio between the shaft52 and a shaft 54 or, when the planetary cage is stationary, will rotateshaft 54 at a higher speed than that of shaft 52.

The output shaft 54 of transmission 53 is connected by gears 55 and 56to the previously mentioned shaft l2. Gear 55 is fixed to shaft 54 whilegear 56 is normally freely rotatable with respect to shaft l2 but may befixed thereto by operation of a pneumatic clutch, indicateddiagrammatically at 57. A sprocket 58 on shaft 54 is connected by meansof a chain 55 to a sprocket 65 journaled on the shaft of a hoisting drum6|. The sprocket 60 may be clutched to the hoisting drum by any suitableclutch, indicated at 62. The complete transmission mechanism, includingthe shafts I2, I, I5, 4|, 52 and 54 and the transmissions and gearsconnected thereto, is preferably enclosed in a single casing, indicatedby a dotted line outline 63, and shown fragmentarily in Figures 2, 3, 4and 5. The extremities of shafts 4| and 54, which project from thecasing, are provided with catheads 63 and 64 respectively.

The transmission construction described above may be selectivelyoperated to meet all conditions encountered in rotary well drillingoperations. Thus, for hoisting the rotary drill stem, clutches 38 and 62are engaged and clutches 43 and 51 are disengaged. If it is desired toemploy both engines for hoisting purposes, clutch |3 is also engaged,otherwise it is disengaged. One or both engines then drive the hoistingdrum through the three two-speed transmissions I4, 5| and 53 in series.Since, for reasons hereinafter pointed out, the speed ratios of thesethree transmissions are identical, a total of four different gearedspeed ratios is available between the torque converters and the drum.

With the mechanism of the present invention, it will not generally benecessary to drive the hoisting drum in reverse because lowering of thedrill stem may be achieved by using the hydrokinetic torque converters 5and 9 as a hydraulic braking means with their output shafts 6 and Irotating in reverse compared with the direction of rotation of the inputshafts 4 and 8, which will be driven by the engines at a speed necessaryto balance theload. For this purpose, it will be understood thatsuitable cooling means for the liquid in the torque converters must beprovided. The preferred cooling mechanism consists of a differentiallydriven fan and radiator unit of the type disclosed in greater detail inapplicant's co-pending application, Serial No. 571,656, filed January 6,1945. However, if it is desired to positively drive the drum in reverse,clutch 38 is disengaged and clutch 51 engaged. The hoisting drum is thendriven either from shaft 1 or shaft I2, or both, through gears 55 and 56and sprockets 58 and 60 in a reverse direction.

During normal drilling operations, it is neces sary to operate the slushpumps and the rotary table 56 simultaneously. This is accomplished bydisengaging clutches i3, 35 and 62 and by engaging clutches and 43.Engine 2 then drives the power take-off pulley 36 for the slush pumpthrough transmission I4, while engine 3 drives the rotary table throughgears 55 and 56, transmissions 53 and 5|, gears 44 and 45, and sprockets41 and 49. The two engines under these conditions operate independentlyof each other and provision ismade for independently changing the speedratios to the two power takeoffs. Thus, by shifting transmission |4, twodifferent speed ratios may be provided for the slush pump take-off. Byshifting transmissions 5| and 53, three different speed ratios may beprovided for the rotary table. In addition, in both cases the automatictorque and speed ratio characteristics of the torque converters areavailable.

When it is desired to reverse rotation of the table, clutches 51 and 52are disengaged and clutches 38 and 43 are engaged. Then one or bothengines may drive the rotary table at either one of two speeds throughtransmission it, both speeds being in a direction reverse to the normaldirection of table rotation when driven through the gears and 56.

As mentioned previously, while all three of the transmissions l4, 5| and53 are of the same type, it is preferred to mount the transmission 53 inreverse relation so that it acts as an overdrive when shaft 52 isdriving shaft 54. This does not change the number of speed ratiosavailable for operation of the various elements of the machine becausethere still remains three two-speed transmissions connected in series.This arrangement, however, has two advantages. First, it reduces themaximum torque on shaft 54 during hoisting operations and, therefore,reduces the size and strength of the transmission parts. Secondly, bymounting the transmission 53 in such a reverse relation, it operates asa step-down transmission during normal table driving operations. Sincein that case shaft 54 is driving shaft 52, this reduces the speedreduction required between gear 44 and table operating sprocket 49 whichwould otherwise be relatively high. While this particular arrangement ofthe transmission 53 is preferred for the reasons stated, it will beapparent that transmission 53 may be mounted in exactly the same manneras transmission 5|, in which event identical speed and torquerequirements may be satisfied by decreasing the size of sprocket 55relative to is transmitted in one direction through them, it

will be in a direction from the low speed shaft to the high speed shaft.However, the form of transmission indicated at H! and shown in Figure 2cannot give two speed ratios when power is delivered through thetransmission from the low speed shaft l5, because in that direction thetorque reaction on the planet cage tends to rotate the cage in the samedirection as the input shaft. One way brake blocks cannot be used toprevent such rotation of the planet cage without also preventingtransmission of power at the 1 to 1 ratio. Accordingly, for that reason,a different form of mechanism is provided in transmissions 5| and 53 toeffect a shift in the speed ratios.

, Referring to Figures 4 and 5, transmissions 5| and 53 omit the one waybrake blocks of transmission |4 and in lieu thereof employ pneumaticallyoperated brake bands for holding the planet cages against rotation inone speed ratio.

Thus transmission I is provided with a brake band 65, one end of whichis adjustably anchored to the casing by an eye bolt 66, and the other isconnected to a pin 61 which is eceentrically fixed to a shaft 6'!journaled on the casing. An arm 08 fixed on shaft 61 is connected to thepiston rod 90 of a pneumatic cylinder and piston unit including a pistonI9 and a cylinder H. The cylinder TI is pivotally connected to. thecasing 63 by a pin 12. A spring 13 normally actuates piston 19 in adirection to apply and hold the brake band applied, as shown in Figure4, thus maintaining the transmission 5| in its low speed ratio forhoisting. By admitting air under pressure to the cylinder throughconduit 14, release of the brake is effected. At the same time, airunder pressure will be admitted, to the annular cylinder 15 which causesengagement of the planet brakes to establish a 1 to 1 speed ratiothrough the transmission. The annular cylinder 15 is identical inconstruction and mode of operation to the cylinder 3| of Figure 2 andhence is not illustrated in detail. Since, to eifect shift oftransmission 5| to its 1 to 1 ratio, air pressure must be admittedsimultaneously to both of the cylinders II and I5, a single valve may beemployed for that purpose.

Transmission 53 is provided with a similar brake band 15 which may beoperated by mechanism identical to that employed to operate brake band95. However, transmission 53 is reversed with respect to transmission SIand it is preferred to hold the transmissions in their low speed ratiofor hoisting purposes by action of springs rather than air pressure.That means that transmission 53 should be held in its 1 to 1 ratio bysprings and shifted to its step-up speed ratio during hoisting by airpressure. The only change in the brake applying mechanism required forthis purpose is to rotate the shaft 6'1" of Figure 4 to a position 180from that shown when connecting it to the arm 98. Then the spring :3will hold the brake disengaged and air pressure will apply the brake. Inview of the minor character of this change, the brake band operatingmechanism for transmission 53 is not eparately illustrated in thedrawings.

The mechanism for operating the planet gear brakes of transmission 53 isshown in Figure 5. As there shown, the brake plate 7! has fixed theretoa collar ?8 on which is journaled by a ball bearing 19 a shifting ring89. A shift lever 8i which is pivoted at 82 has a yoke at its upper endwhich is pivoted to the ring 80 by aligned pins 83. The opposite end ofthe lever is connected to a piston rod 84 having a piston 85 in acylinder 89. The cylinder is pivotally connected to the housing by a pinEl. A spring 88 normally holds the piston in its illustrated position inwhich the planet brakes are engaged and the transmission 53 is in its 1to 1 ratio. When air under pressure is admitted simultaneously tocylinder 89 through conduit 89 and to the cylinder which applies brake19, the transmission is shifted to its other speed ratio.

Except as indicated above, transmissions 5| and 53 are identical totransmission !4 and hence need not be further described.

Means are provided in accordance with the present invention forautomatically synchronizing the engines 2 and 3 during hoistingoperations while leaving the driller free to adjust the throttles of theengines to produce any desired performance. Synchronization of theengines is achieved by the mechanism shown princip l y in Fi r s 6 hrouh 0 and also to some degree in Figure 1. Thus referring to Figure 1, thethrottles for the two engines, which are indicated diagrammatically at99 and'9I, are operated by a pair of Bowden Wires 92 and 93,respectively, which are connected respectively to the lower ends of apair of hand operated throttle levers 94 and 95, shown best in Figure 9.Lever is carried by a sleeve 96 which is freely journaled on a shaft 91carried by a suitable'supporting frame work 98. The shaft 91 is fixedagainst rotation. The left-hand end of sleeve 96 is provided with an arm99 in which mounted a suitable spring detent I09 adapted to co-operatewith an arcuate toothed ratchet bar I9I fixed to the frame work 98 inorder to hold the throttle lever 95 in any one of a plurality ofadjusted positions.

The throttle lever 94 is similary fixed to a sleeve I92 which is freelyrotatable upon the shaft 91. The sleeve I92 likewise is provided with anarm I93 carrying a spring pressed detent I 94 adapted to co-operate withan arcuate toothed ratchet member I05 fixed to the frame work 98. Whenthe sleeve IE2 is in the position illustrated in Figure 9, the lever 94may be employed to adjust the throttle of engine 2 independently of thethrottle position of engine 3 which is controlled by the lever 95. Suchoperation will be required when the engines are independently drivingthe slush pump and rotary table, respectively.

Means are provided for placing the control of the throttles of bothengines under the infiuence of lever 95, and this means automaticallymaintains the two engines in synchronism inorder to insure that the twoengines will carry equal shares of the load during the hoistingoperations. This is accomplished by making the sleeve I92 of lever 94slidable upon the shaft 9'! to cause engagement between a plurality ofdog clutchteeth I96 on sleeve I02 with mating teeth I91 on a sleeve I09which is freely rotatable upon the shaft 91. A spring pressed detent I99is provided Within the sleeve I92 for engagement with either one or apair of V-shaped grooves Ill! and III formed in the shaft 9! in order tomaintain the sleeve 92 in either one of its, two axial positions ofadjustment.

When the sleeve I02 is shifted to the left to cause engagement betweenthe clutch teeth I96 and I91, the spring pressed detent I94 is pulledout. ofcontact with the arcuate ratchet member I95- so that the ratchetmechanism no longer eireets the operations of the lever 94. In order toinsure re-engagement of the detent I94 with the ratchet member I95, theedge of the areuate ratchet member I95 is beveled at H2 and the detentI04 is provided with a shoulder II 3 adapted to limit the projection ofthe detent from the arm I93, as best shown in Figure 10. Sleeve 96 oflever 95 is provided witha seQOIld arm II4 which is connected through asynchronizing mechanism hereinafter described to an arm II5 on thesleeve I98 in such a manner that movements of the lever 95, which aredirectly eifective to shift the throttle 9I of engine 3, alsocorrespondingly shift the throttle 99 of engine 2 through the mechanismwhich insures that both engines will also be operated at the same speed.

Thus, as best shown in Figures 6 and 9, the arm II4 on sleeve 96 isconnected by a Bowden wire IIG to a lever II! which is pivotedintermediate its ends on a pin H8. The opposite end of the lever I I1 isconnected by means of a Bowden wire II9 to the arm II5 on sleeve I08. Asa result of this arrangement, counterclockwise swinging movement of thelever 95, as viewed from the right-hand end of the shaft 91, produces asimilar movement of sleeve I08 and, therefore, of sleeve I62, which isclutched thereto, thus opening the throttles of both engines to the samedegree. In order to modify the throttle movement of engine 2 to anyextent necessary to maintain the engines in synchronism, the pin II8 oflever II1 is adjusted vertically by a differential mechanism which isresponsive to any difference between the speeds of the shafts 4 and 8.

Thus, as best shown in Figure 8, shaft 4 which is mounted within asuitable housing I20 is provided with a multiple thread worm I2I adaptedto drive a worm wheel I22 fixed to a shaft I23. Shaft 1, which issimilarly positioned within the housing I24, carries a worm I25 whichdrives a worm wheel I26 fixed to a shaft I21. The worms I22 and I25 areof opposite hand with the result that the shafts I23 and I21 are rotatedin opposite directions and at speeds directly proportional to the speedsof the shafts 4 and 8, respectively. The shafts I23 and I25 are theinput shafts of a differential gearset mounted within a housing I28.Thus shaft I23 carries a bevel gear I29 adapted to mesh with a pair ofbevel gears I36 and I3I journaled on a cage I32 which is freelyrotatable upon the shafts I23 and I21. Shaft I21, in turn, carries abevel gear I33 which meshes with the bevel gears I36 and I3I. The cageI32 carries a bevel gear I34 which meshes with a bevel gear I35 carriedby a vertical shaft I36. As best shown in Figures 6 and '1, the shaftI36 is provided with a threaded section I31 which is threaded through asliding block I38 which carries the previously mentioned lever pin I I8.Block I38 has a sliding dovetail connection I33 with a vertical supportI40 which is fixed to the casing I28 of the differential. The threadedportion I31 of shaft I36 is of larger diameter than the remainder of theshaft and terminates below the upper extremity of the shaft. A coilspring I4I surrounds the shaft between the block I33 and the casing I28,thus exerting an upward force on block I38 for a purpose hereinaftermentioned.

The arrangement of the gearing for the shafts I23 and I21 is such thatwhen the shafts 4 and 8 are driven in the same direction at the samespeed by the engines 2 and 3, bevel gears I29 and I33 will operate inopposite directions at the same speed and the cage I32 will remainstationary, consequently, there will be no movement of the sliding blockI38. In the event that the speed of shaft 4 exceeds that of shaft 8,shaft I23 will rotate at a more rapid rate in clockwise direction, asviewed in Figure 6, than will the shaft I21 in the opposite direction.Consequently, the cage I32 will rotate in a counterclockwise direction,as viewed in Figure 6, and effect a clockwise rotation of the shaft II2, as viewed in Figure 1. Since the threaded portion I31 of the shaftI36 has a right-hand thread, this will cause the block I38 to moveupwardly. Since during such movement the left-hand end of lever II1 doesnot change position, the effect of the movement is to move theright-hand end of lever II1 upwardly, thus partially closing thethrottle 90 of engine 2. This closing movement will continue until thespeed of the shafts 4 and 8 becomes the same, at which time rotation ofthe shaft I36 will stop. In the event that shaft 4 tends to rotate at alower speed than shaft 8, the reverse effect will be produced.

The above described synchronizing mechanism performs two importantfunctions when'both engines are used for hoisting. In the first place,it insures that the two engines will share equally in supplying thepower required. This follows from the fact that the two engines drive acommon shaft through separate torque converters.

If the two converters are the same in construction, as they should be,then they will transmit exactly the same torque because their inputshafts are rotating at the same speed and their output shafts are alsorotating at the same speed. In addition, the synchronizing mechanisminsures that both torque converters will be operating at the same speedratio, and hence act like a single converter of double capacity. This isimportant because, as hereinafter pointed out, the design of thetransmissions I4, 5| and 53 and the mechanism for controlling them iscorrelated with the speed ratio characteristics of the converters.

Under some conditions, as during starting of the engines, a very greatdivergence in the speeds of the two engines may exist for a shortperiod. Consequently, means are provided for limiting the effect of thedifferential mechanism upon the throttle of engine 2. This isaccomplished by making the threaded section I31 of the shaft I36relatively short and of larger diameter than the shaft. Consequently,the block may thread off either end of the threaded portion. As soon asthis occurs, its axial movement will cease and it will remain in thatposition until a reverse rotation of the shaft I36 occurs. Since theblock is guided by the dovetail I39, it will always remain in positionto re-enter the threaded portion of the shaft. -When it is threaded offthe upper end of the threaded section I31, gravity will tend to bring itback into threaded engagement. When it is threaded off the lower end ofthe threaded section I31, the previously mentioned spring I4I will exertsufficient force to effect the ill threading engagement. If desired, aspring similar to the spring I II may be provided for the upper end ofthe shaft I36.

As is well known, the torque converters 5 and 9 provide an automatictorque ratio and speed ratio adjustment which is peculiarly advantageouswhen utilized in the drive of a hoisting drum, particularly during thestart of a hoisting operation, because it provides a high startingtorque and an automatic decrease in the torque as 5 the load is speededup. This follows from the characteristic torque speed ratio curveillustrated in Figure 21. However, the eificiency of hydrokinetic torqueconverters is relatively low except within a relatively limited range ofspeed ratios, 55 as shown by the characteristic efiiciency curve alsoincorporated in Figure 21. Accordingly, while the torque converter driveis of great value for starting purposes, it is unsatisfactory for thebulk of the hoisting operation unless the speed ratio of the converteris maintained within the eflicient range. Accordingly, there isincorporated in the present invention automatic means for controllingthe operation of the three twospeed transmissions in such a manner as tomaintain the torque converter speed ratio within the range in which theconverter operates near its maximum efficiency.

While the efficiency curves for hydrokinetic torque converters ofdifferent designs vary somewhat, the particular curve illustrated inFigure 21 is generally representative. Accordingly, it will be employedfor purposes of illustrating the principles of the present invention.Assuming that the converters to be employed have an efficiency curvecorresponding to that illustrated in Figure 1 1 21, it will be notedthat the range of speed ratios within which the efficiency equals orexceeds 80 percent extends from a speed ratio of the output shaft to theinput shaft of .25 to a ratio of .50. If the torque on the input shaftincreases to such an extent that the speed ratio of the converter fallsbelow .25, the efiiciency drops rapidly. Likewise, if the torque on theoutput shaft of the converter decreases to such an extent that the speedratio of the converter exceeds .50, there is a rapid drop in efficiency.These two ratios 'may, therefore, be selected as the minimum and maximumefiicient speed ratios for purpose of designing the transmissionmechanism. Thus, automatic means are provided which, in response to thespeed ratio of the converter, will shift the transmission mechanism intoa higher gear ratio when the speed ratio of the converter tends toexceed the maximum efficient ratio (.50 in the above example) and shiftthe transmission into a lower speed ratio when the speed ratio of theconverter tends to fall below the minimum efficient ratio (.25 in theabove example). This mechanism controls each of the three transmissionunits I4, 5| and 53 individually and is so arranged as to provide theproper successive step by step change in speed ratio through all four ofthe available ratios provided by the complete transmission mechanism.

For example, since for the torque converter: whose eiliciency curve isillustrated in Figure 21, the maximum efiicient speed ratio is justtwice the minimum efficient speed ratio, each of the three transmissionsI4, 5| and 53 may be so constructed that one of its two speed ratios istwice that of the other. Consequently, for a given engine speed, if as aresult of a reduction in load, the speed ratio of the converter tends toexceed .50, and one of the three transmissions is then shifted to itsnext higher speed ratio, the speed and torque of'the hoisting drum willnot be changed but the output speed of the converter will be cut in halfand the output torque doubled, thus bringing the torque converter backto a speed ratio of .25, which is its minimum efficient speed ratio.Conversely, if at any time the load increases to such an extent that thespeed ratio of the converter tends to fall below .25 and as aconsequence one of the transmissions is shifted to a lower speed ratio,the torque and speed of the drum BI will not change but the output speedof the converter will double and the torque be cut in half, thusbringing the converter speed ratio back to .50. In all positions ofadjustment of the transmission, the speed ratio of the converter mayfluctuate automatically in response to changes in load between the speedratio of .25 and .50 without any transmission shifts. Since, with thepreferred type of two speed transmission unit disclosed in the drawings,one speed ratio is always a direct drive or 1 to 1 ratio, then toaccomplish the above results the other ratio should be 2 to l.

The mechanism by which the transmission is automatically shifted is bestillustrated in Figures 1 and 11 through 15. Thus, as best shown inFigure 11, the transmission control mechanism includes threedifferentially operated electrical switches, indicated generally at I42,I43 and I44, mounted on a common mounting plate I45. Each of the threedifferential switch mechanisms includes a geared differential which maybe identical in construction and mode of operation to the differentialillustrated in Figure 8. Thus, best shown in Figure 12, the differentialswitch mechanism I42'includes a differential I46 havin mission units.

a pair of input shafts, one of which is connected to a flexible driveshaft I4! and the other to a bevel gear I48. The differential also has avertically extended output shaft I corresponding to the shaft I36 ofFigure 8. The bevel gear I48 of differential switch I42 and thecorresponding bevel gears I and I5I of the identically constructeddifferential switch mechanisms I43 and I44 mesh with a common bevel gearI52 which is mounted on a vertical shaft I 53 that is driven by aflexible shaft I54. The differential switch mechanism I43 has a flexibleinput shaft I 55, while the differential switch mechanism I44 has asimilar flexible shaft I56.

Flexible shaft I54 is connected to the end of shaft I23 in Figure 8 and,consequently, is driven at a speed proportional to the speed of shaft 4.Flexible shaft M1 is connected by a pair of gears I51 and I58 to theoutput shaft I5 of transmission I4. Flexible shaft I is connected by apair of gears I59 and I60 to the output shaft 52 of transmission 5|.Flexible shaft I56 is connected by a pair of gears I6I and I62 to theoutput shaft 54 of transmission 53. Thus, the input shafts I41, I55 andI56 of the three differential switch mechanisms are driven at speedsproportional to the speedsof the output shafts of the three trans-Moreover, the drive connections are such that during hoistingoperations, the direction of rotation of the fleximle shafts I41, I55and I56 are opposite to the directions of rotation of the bevel gearsI48, I50 and I5I. Consequently,

for any given differential switch mechanism, the

speed of the third or output shaft Will be zero when the speeds of thetwo input shafts are equal. Moreover, the gearing in the driveconnections of the input shafts of the three differentials is such thatwhen anyone of the transmission units and all preceding transmissionunits are in their low speed ratios and the speed ratio of theconverters approaches the maximum efficient ratio, the two input shaftsof the differential associated with said one transmission unit willrotate in opposite directions at approximately the same speed; and thesame result will occur when anyone of the transmission units and allpreceding transmission units are in their high speed ratios and thespeed ratio of the converters approaches the minimum efficient ratio.Thus, when the one transmission and all preceding transmissions are inlow gear, the output shaft of the differential associated with said onetransmission unit will rotate in one direction when the speed ratio ofthe converters is less than the maximum efficient ratio and in theopposite direction when the speed ratio exceeds that ratio.

Likewise, when said transmission unit and all preceding units are intheir high gear ratios, the output shaft of the differential associatedwith that transmission unit will rotate in said one direction when thespeed ratio of the converters is less than the minimum efllcient ratio,and in said opposite direction when the speed ratio exceeds the minimumefficient speed ratio. Accordingly, means are provided which operate inresponseto a reversal of the direction of rotation of the output shaftof each differential mechanism for shifting the associated transmissionto its low speed ratio when the output shaft of the differential tendsto rotate in said one direction, and to its high speed ratiowhen thedifferential output tends to rotate in said opposite direction.

By so effecting the shift at or near the speed at which the output shaftof each differential mechanism is zero, it is possible to insure thatthe shift of the transmission will always occur at the desired converterspeed ratio regardless of variations in the speed of the input shaft ofthe torque converter. This result cannot be obtained if the transmissionshifting mechanism is constructed to operate in response to apredetermined speed of the differential output shaft unless that speedis relatively close to zero as compared to the speeds of thedifferential input shafts.

While any suitable mechanism responsive to the reversal of the directionof the rotation of the output shafts may be employed to effect a shiftof the transmissions, the preferred mechanism illustrated in thedrawings is in the form of an electrical switch, which is driven by aslipping clutch mechanism from the output shaft of the diiferential, andwhich controls the electrical circuit for a pneumatic valve that, inturn, effects the necessary shift of the transmission. Thus, as bestshown in Figures 12, 13 and 14, the output shaft I49 of the differentialI46 carries a multipole permanent magnet 63 which is freely rotatablewithin a housing I64 formed of an electrically conductive material andfixed to an independently journaled shaft I 65. he multi-pole permanentmagnet I63 and its housing I64 form an eddy current magnetic clutch of awell known type, and may be of any desired or conventional construction.As is well known, rotation of the multi-pole permanent magnet within thehousing tends to induce eddy currents within the housing I64 which arecut by the moving lines of force emanating from the permanent magnets.Consequently, the member I63 transmits a driving t-orgue to the memberI64 but may slip relative thereto to an unlimited extent. Fixed in anysuitable manner to the housing IE4 is a cylindrical pin I66 formed ofinsulating material. The pin I66 projects through a slot I61 formed in aswitch mounting plate I68, which constitutes the top of an enclosedhousing I69 for the eddy current clutch. The upper extremity of the pinI66 is provided with a transverse slot I16, as best shown in Figure 14,and in that slot is a tightly fitted anelectrically conductive contactbar I1I which is adapted to complete a circuit between a pair ofstationary contacts I12 carried by the switch mounting plate I68 whenthe pin I66 is at the lower end of the slot I61, as viewed in Figure 13.A coil Spring I13 extends from a bracket I14 to the pin I66 and acts toyieldingly retain the pin its at either extremity of the slot I61 byreason of the fact that the spring I13 has an over-center action. Thebracket I14 is connected by means of a stove bolt I15 to the switchmounting plate I63; and the position of the bracket may be adjustedalong the slot I16 in the mounting plate I65 and also by reason of theslot I11 in the bracket I14 so that it assumes any desired position.Thus, if desired, the position of the bracket may be so shifted that thesole tendency of the spring is to urge the pin in one direction in slotThe arrangement of the gearing to the differential input shafts is suchthat when the transmission unit with which the differential isassociated and all preceding transmission units, if any, are in low gearand the speed ratio of the converter reaches approximately its maximumefficient ratio, or when the transmission units are in their high ratioand the speed ratio approaches approximately its minimum efficientratio, shaft I48 will remain stationary. If those speed ratios areexceeded in either case, shaft I49 will rotate in a direction to causepin I66 to 1 sion SI.

haust port I82 and blocks line I8I.

move downwardly in slot I61, as viewed in Figure 11. If the speed ratiofalls below those ratios in either case, shaft I49 will rotate in theopposite direction and tend to move pin I66 upwardly in slot I61. If thespring I13 is designed to have an over-center effect tending to hold thepin I66 at either end of the slot I61, the spring should be exceedinglylight so that a relatively slow rotation of the shaft I49 in eitherdirection will overcome the force of the spring and shift the pin I66.

As soon as the pin reaches the position illustrated in Figure 13, theelectric circuit between contacts I12 is completed and the transmissionis shifted from its low speed ratio to its high ratio for hoisting.Immediately after the shift, the speed ratio of the converter will dropback from its maximum eflicient ratio to its minimum efficient ratio,but because the engine speed and the output speed of the transmissionare not reduced by such shift, the pin I 56 will remain in the positionillustrated in Figure 13 until the speed ratio of the converter fallsbelow its minimum efficient ratio. In such event, the direction ofrotation of the shaft I49 reverses and the pin is swung upwardly in slotI61, as viewed in Figure 13, thus breaking the circuit between contactsI12 and effecting a shift of the transmission back into its low speedratio. It should be noted that the differential switch mechanism I42controls the shifting of transmission I4, differential switch I43controls transmission 5| and the differential switch I44 controlstransmission 53.

The valves which control operation of the three transmissions and theelectrical control circuit therefor are shown diagrammatically in Figure15. Thus, the three transmissions are indicated diagrammatically inFigure 1 by their reference numerals I4, 5| and 53. Transmissions I4 andSI are so constructed that they are normally in their low speed ratio of2 to 1, but will shift to their high speed ratio of 1 to 1 when airunder pressure is admitted through the air inlet lines 34 fortransmission I4 and line I18 for transmis- Line I18 is in communicationwith the interior of cylinder 15 which applies the planet clutches oftransmission 5I and also communicates through the branch line 14 withthe cylinder 1Iwhich controls the brake band of tra smission 5I, aspreviously described.

Transmission I4 is controlled by a three way valve I19 which is suppliedwith air under pressure from a line I through a branch line I and whichnormally connects line 34 to the ex- The valve employed is of thesolenoid operated type being controlled by a solenoid I83. When thesolenoid I83 is energized, the exhaust port I82 is blocked and line I8Iis connected to line 34, thus causing a shift of the transmission I4 toits high gear ratio of 1 to 1. .A similar valve I84 controls theshifting of transmission 5i and is operated by solenoid I85. Since inthe preferred form of the invention transmission 53' is reversed withrespect to the other two transmissions, its low gear ratio for hoistingpurposes is a 1 to 1 ratio and its high gear ratio is a 1 to 2 ratio.However, since this transmission is normally in its 1 to 1 ratio andshifts to 2 to 1 when air pressure is applied, the control valve I86 fortransmission 53 is identical to the valves I19 and I84. Thus valve I8 5normally blocks the line I81 and connects line I 88 to the exhaust portI89. When the solenoid I96 is energized, the valve connects lines I81and I88 and blocks the'exhaust port. Line 588 communicates with line 89which supplies air to the planet clutch operating cylinder 86 oftransmission 53 and also with line I91 which supplies air to thecylinder, indicated diagrammatically at I92 in Figure 15, which appliesbrake band 16 of transmission 53. Solenoid controlled three way valves,either pilot or directly operated, are standard articles of commerce andany desired type may be employed for control of the three transmissionsso long as they function in the manner indicated above. Consequently,the details of construction form no part of the present invention andneed not be further described.

As shown in Figure 15, the solenoids I 33, I85 and I90, which operatethe transmission shifting valves i153, I84 and I8, respectively, areconnected in parallel between a, pair of electric power lines I93 andI94 by lines I95, I96 and I91. The three lines I95, I96 and I91 containnormally open contacts of relays I98, I99 and 209, respectively, whichrelays, in turn, are connected in series, respectively, with thestationary contacts of the differential switches I42, I 43 and I44 bymeans of parallel lines 2E3I, 202 and 203. As a result, closing of anyone of the different switches will energize the associated relaysolenoid and shift its transmission unit to the high ratio, and viceversa. If desired, the relays I518, I99 and Ziill may be of the delayedclosing type and be adjusted to close within a very brief-intervalfollowing closure of the differential switch contacts.

This will prevent shifting of the transmissions on a momentary loadfluctuation. The contacts are preferably of the quick opening type sothat no delay in shifts to lower gear ratios will occur.

In order to obtain the desired operating characteristics for thehoisting drum, it is necessary to correlate the design of thetransmission mechanism with the efficiency and torque curves of theconverter. The curves so employed should preferably be the curve ofconverter output torque for a fixed throttle setting of the particularengine which is used plotted against converter speed ratio, and theconverter efficiency plotted against converter speed ratio for the samefixed engine throttle position. The curves of Figure 21 are generallyrepresentative although different engines and different converters willhave slightly different characteristics and, therefore, the actualcurves for the engine and converter combination which is to be usedshould be employed.

To obtain the necessary correlation in design, it is necessary toselectfirst the speed ratios of the converter at which it is desired toshift the transmission. These are referred to as the maximum efficientspeed ratio and the minimum efficient speed ratio. These ratios shouldbe on opposite sides of the speed ratio of maximum efficiency and in arange Where the efficiency is fairly high. Preferably the ratios shouldbe at points on the efficiency curve where the efficiencies areapproximately the same. Thefirst transmission unit I4 is then sodesigned that for a given engine speed, when the transmission unit is inits low gear ratio and the converter is operating at its maximumefiicient ratio, a shift of the transmission to its high gear ratio willoccur Without any decrease in the ratio of the sped of the output shaftof the transmission to the input speed of the converter, and preferablywith as little increase in that ratio as possible. Likewise, when thetransmission is in high gear and the converter is operating at itsminimum efiicient speed ratio, a shift of the transmission to its lowgear ratio occurs without any increase in the ratio of the speed of theoutput shaft of the transmission to the input speed of the converter,and preferably with as little decrease in that ratio as possible. Itwill be apparent to those skilled in the art that suitable transmissionratios may be readily selected to satisfy these conditions for any givenmaximum and minimum efficient speed ratios. In the ideal case, however,the maximum and minimum emcient speed ratios are those at which theconverter efliciency is the same and the ratio between the two speedratios of the transmission unit equals the ratio between the maximum andminimum efficient speed ratios.

Having determined the transmission ratios and the maximum and minimumefficient speed ratios for transmission It, it is only necessary toprovide the proper speed ratios in the drives to the differential switchM2 to effect a shift of the transmission at the correct converter speedratios. In the ideal case, assuming that the switch would operate atexactly the point of reversal of the output shaft M9, the gearing in thedrives for shafts IEQ and I l? should be such that when the converter isat its maximum emcient speed ratio and the transmission is in low gear,the shafts I55 and I4? will rotate at the same speed in oppositedirections. The same condition will then exist in the ideal case whenthe converter is at its minimum efficient speed ratio and thetransmission is in its high gear.

If, as in the embodiment of the invention illustrated in the drawings,the complete transmission includes a plurality of two speedtransmissions connected in series, the same considerations govern thedesign of each transmission unit. The fact that the transmission I4precedes transmissions EI and 53 does not complicate the problem becausetransmission 5i never shifts in either direction except whentransmission I4 is in its high gear ratio and transmission 53 does notshift in either direction except when transmissions I4 and 51 are bothin their high gear ratios.

In order to obtain a maximum ultilization of the efiicient range of thetorque converter, all three transmissions should have the same ratiobetween their two speeds and shift at the same speed ratios of theconverter. If they are so constructed and all of the transmissions arein their low gear ratio, then the mechanism will be effective to shiftthe transmission units into their high gear ratios successively as thehoisting load falls off in such a manner as to maintain the speed ratioof the converter within its efficient range. However, if two or more ofthe transmission units are in their high speed ratios and the loadincreases sufficiently to reduce the converter speed ratio to theminimum efiicient ratio, all of the transmission units which are intheir high ratio will shift to their low ratio simultaneously. If such ashift is more than necessary, one or more transmission units will thenshift back to their high ratios, as required. If it is desired to avoidthe double shifting thus induced on shifts to higher ratios, themechanism previously described may be adjusted or modified slightly inany one or several ways to produce successive shifts of the transmissionunits to their high ratios.

For example, the springs N3 of the differential switches'may be soadjusted that on an increase in hoisting load, when all threetransmission units are in their high ratios, switch I44 will open beforeswitch I43 and switch 553 will open before switch I42. This can be doneby providing progressively stronger springs for the 17 switchesI42, I43and I44 or by adjusting the spring brackets I14 along slot I16 so thatwhen the switches are closed, the spring for switch I44 has a greaterover-center effect than that of switch I43, etc. A second method ofachieving this result is to distribute the shifting points for the threetransmissions at slightly spaced intervals along the efficiency curve.This amounts to a selection of slightly different maximum and 18 torquecharacteristics shown on the following table, assuming a constant enginespeed of 1600, R. P. M., a constant engine torque of 1500 foot pounds (2engines), and a speed ratio of to 1 between shaft 54 and the hoistingdrum. With an engine speed of 1600 R. P. M., the bevel gears I48, I50and I5I of the differential switches will operate at 800 R. P. M. and,therefore, the output shafts of the differentials will be stationaryminimum efficient speed ratios for the three when the other differentialinput shafts (I41, I55 transmissions. This can be done either byslightand I56) rotate at 800 R. P. M. The speeds of 1y modifying thespeed ratios in the drives to these other differential input shafts areshown in the differential switches, even though the speed the columnheaded Difi. Input.

Transmission Transmission Transmission speed i i-R. P. M. 51-R. P. M..P. M. Drum Drum Hoisting Conditions Ratio of speed Turque omverterInput Out- Diff. Out- Diff. Out- Difi. Ft'ibs put Input put Input putInput {Stall 0 -'0 0 0 0 0 0 0 0 150,000 Low Gear Min. Eff. Speed R .25400 200 400 100 197 100 07 90, 000 Max. Efi. Speed R .50 800 400 800 200394 200 194 40 45,000 Min. E11. Speed R .25 400 400 800 200 304 200 10440 45,000 2nd Gear {Main Eff. Speed 12..-- .507 812 512 1, 624 400 800405 394 81.2 22,500 3rd Gear {Min Eff. Speed 12.... .254 405 400 812 400800 405 394 81.2 22,500 Max. Efi. Speed R .515 824 824 1, 548 824 1, 524824 800 155 11,250 High Gear {titzttittiihz 128 iii 36% 1233 36% 1,2531,23% 1,233 8 tii ratios of the transmissions are all the same, or Itwill be observed that the above table shows by providing slightlydifferent speed ratios in the successive speed conditions as the torqueload the three transmissions. However, if either of on the hoisting drumfalls off from maximum these last two expedients are employed, carestall torque with all three of the transmission should be taken toinsure that for none of the units initially in their low gear ratios.The transmission units is the ratio of the transmission transmissionsI4, 5| and 53 shift successively to output shaft speed to the converterinput speed at their high speed ratios when the differential inle s atmin m m fiic n speed r i in low gear put shafts I41, I55 and I56,respectively, reach than at maximum efficient speed ratio in high aspeed of 800 R. P. M. Thus, it will be noted gear. that the differentialinput for the switch I42 of The f w n ill r v x mpl is iven totransmission I4 does not reach a speed of 800 further elucidate theprinciples outlined above: R. P. M. until the torque converter is at itsmaxi- If the converter eificiency curve is assumed to be r m em i ntpeed rati After the shift of that Of Figure 21 and it s esired to p thei transmission I4 has been effected, the speed of c nv r r w h the speedio ran e t whi h the differential input remains at 800 R. P. M. so itsefiiciency is 80% m then the mum long as the torque load on the drumremains the efl c Speed ratio y taken as 5 and the same and theconverter operates at its minimum maximum efficient Sp ratio y be takenas 45 efficient speed ratio in second gear. On subse- .50. Since theratio between these two converter quent d ti i l d, th differentialinput speed ratios is 2 to 1, then the ratio between the for t mis ion[4 always remains at a speed two speed ratios of the transmission mayalso i excess of 300 R. M" consequently, the t be made 2 to 1. Si ce,With the preferred form mission is maintained in its high speed ratio ofof transmission unit disclosed above, one speed 1 t 1; t t t t t thedifierential ratio is necessarily a 1 to 1 ratio, then the other iputfor t i i l4 che the shifting speed may be a 2 to 1 ratio.Transmissions I4 and 5!, of 809 p M" the differential inputs f rtranstherefore, each give a 2 to 1 speed reduction for missions 5 and 53are n b l t hifti hois when in low gear- Transmission speed,consequently, only one transmission will being similar but reversed, hasa l to 1 ratio in 55 be hifted 1 gear and a 1 to 2 overdrive in highgear for As the load continues to fall off, the differenhoisting- Allthree transmissions are normally tial input for transmission 5| reachesthe shiftin their low gear ratios giving a total geared ing speed of 800R. P. M. when the converter is ratio of 4 to L at its maximum efficientspeed ratio and the If it is assumed that the Speed ra't1,betweentransmission is in second gear. After shifting, the Output of theconverter and the Input 9 the speed of the differential input fortransmisti'ans'mission is 1 to and that the speed who sion 5| remainsunchanged at 800 R. P. M. but between the engine shaft 4 (or 8) andbevel gee-u the converter drops back to its minimum efficient of Figure11 is 2 to then the speed ratlo speed ratio In this case the minimumefficient between the shaft I5 and shaft I41 of Figure 11 {i5 speedratio is .254 rather than .25 due to the should be 1 to 2. If all threetransmissions were g t th t th eed m m hcation between the to shift atthe same maximum efficient speed 8 Sp output shaft to transmission 5|and the Input ratio, then the speed ratio between shaft 52 and e shaft55 to the differential has been modified shaft I55 of Figure 11 shouldbe 1 to 2, and the I a speed ratio between shaft 54 and shaft I56 shouldin the manner described above fol the purpose be 1 to 1. However, inorder to insure successive shifts into low speed ratio, the last tworatios are made 1 to 1.97 and 1 to .97.

A mechanism having the above specified ratios will operate automaticallyto give the speed and of insuring successive shifts of the transmissionsinto their low gear ratios on increases in the hoisting load. Note thatat the time transmis-'- sion 5! is shifted, the differential input fortransmission 53 is less than shifting speed. More- 19 over, aftertransmission has shifted to .its high gear ratio of 1 to 1 and the loadfurther decreases, the speed of the differential input shaft fortransmission 5| never falls below800;R: P. M., consequently, thetransmission remains. in its high speed ratio.

When on further reduction of load in third gear the converter reachesits maximum efficient speed ratio, the differential input totransmission 53 attains its shifting speed of 800 .R. P..M. and thecomplete transmission mechanism shifts to its high gear ratio withoutany change in the speed of the differential input for transmission 53until further reductions in the hoisting load occur.

It will be noted from the above that the-maximum and minimum efficientspeed ratios for each of the three transmissions are different as aresult of the modification of the speed ratios between the transmissionoutput shafts and the differential input shafts for each transmission.This modification is made in order to prevent simultaneous shifting ofall three transmissions to their low gear ratio when all transmissionsare in their high gear ratio and the load increases; Thus, as shown onthe table, when the converter is at its minimum efiicient speed ratio inhigh gear, the only differential input shaft which is rotating at 800 R.P. M. is the shaft for the differential of transmission 53,consequently, only that transmission will shift to low gear asthe loadincreases. The same thing is true when the converter is at its minimumefficient speed ratio in third gear at which time only the differentialinput for transmission 5! is operating at 800 R. P. M.

The speeds given in the above table are based upon the assumption thatthe engines are operating at a speed of 1600 R. P. M. at all times. Inactual practice, it is preferred to fix the engine throttles at adesired point and allow their speeds to vary in accordance withvariations in the torque load imposed upon them, since that practiceimproves the character of the efficiency curve of the converter. Thiswill result in a slight reduction in the speeds given in the table forthe minimum efficient speed ratio. In addition, it may be desirable toadjust the throttle position from time to time for purposes ofcontrolling the speed of the hoisting drum.

Any changes in engine speed which result from either of these factorswill not change the speed ratios at which the several transmission unitsare shifted so long as the differential switch mechanism is effective toopen or close the control switch contacts at exactly the point ofreversal of the differential output shaft, because the differentialdrives to each differential switch will change in speed to the sameproportion. For that reason, the differential switch mechanisms arepreferably made as sensitive as is practically possible.

With the particular form of differential switch illustrated, sensitivitymay be increased to any desired extent by increasing the strength of themagnetic clutch, increasing the speed ratio between the differentialhousing and the differential output shaft, increasing equally the speedratios to the differential input shafts, and decreasing the strength ofthe over-center spring connected to the movable contact of the switch.By any one or more or these expedients, the difference between thespeeds of the input shafts of the differential, which will be requiredto effect a shift of the movable contact, may be reduced 20 to such asmall percentage of the speeds of the differential input shafts thatchanges in the converter input speed will have a negligible effect uponthe speed ratios at which the respective transmissions shift.

It should also be noted that at any appreciable difference in speeds ofthe input shafts of the differential switches required to effect a shiftof the switch contact will, in effect, shift the converter speed ratioat which the transmission shifts to a value different from that whichexists when the differential input shafts are rotating at the samespeed. Accordingly, allowance for that factor should be made indesigning the transmission mechanism.

It will be observed that there is provided in accordance with thepresent invention a fully automatic transmission mechanism effective tomaintain the speed ratio of a hydrokinetic torque converter which isemployed in the mechanism within a predetermined speed ratio range, andwhich will provide a wide range of torques and speeds automatically asrequired by the load imposed on the mechanism. The broad principles ofthe mechanism may be realized by the use of any form of change speedgearing provided it is controlled in the manner described above, and anydesired number of geared speed changes may be utilized depending uponthe total range of load which must be dealt with. In the particularexample set forth above employing three twospeed transmissions connectedin series, an automatic range of drum speeds is provided between zeroand 320 R. P. M. with a corresponding drum torque range from 150,000 ft.lbs. to 5,625 ft. lbs. neglecting friction and mechanical losses otherthan those encountered in the hydrokinetic torque converter. v

The automatic control mechanism for shifting the transmission at thedesired converter speed ratio is operated independently of the enginespeed and, consequently, the engine throttles may be adjusted as desiredto meet any requirements encountered. Thus, for example, the enginethrottles may be adjusted to such a position that the mechanism merelyholds the load in a stationary position or controls the rate of .itsdescent. Likewise at the end of a lowering operation, by slightlyopening the engine throttles, the mechanism will operate as a brake,thus eliminating the need for hydrokinetic brake mechanisms frequentlyemployed in deep well drilling operations.

.As previously indicated, the preferred form of mechanism illustrated inthe drawings is not only adapted for automatic hoisting operations ofthe type required during rotary well drilling operations but is alsoeffective to operate the slush pump and rotary table during drillingoperations. The change over of the transmission from hoisting todrilling is readily effected by means of a control lever 204, shown inFigure 16, and the associated mechanisms, shown in Figures 15 through20. Thus, as shown diagrammatically in Figure 15, the line I95 whichcontains the solenoid I83 of the control valve I19 of transmission I4 isprovided with a. normally open switch 205. The line I96 which containsthe solenoid I85 of control valve I84 contains a nor-- mallyopen switch296, and line I91 for solenoid I of valve I80 contains a normally openswitch 201. As best shown in Figure 16, the three switches 205, 206 and201 are of the push button type having movable plungers controlled by acam 208 fixed to the shaft 209 which carries the control handle 204. Theform and arrangement of the cam 208 is such that it depresses theplungers of switches 205, 206 and 201, thus holding the switches inclosed position when the control handle is in the solid line positionillustrated in Figure 17. The handle is shifted to that position inorder to place the transmission under the influence of its automaticcontrol mechanism.

If it is desired to disconnect the automatic control mechanism from thetransmission and place it under the influence of manual control, lever204 is pulled into the solid line position 2 I 0. This disengages thecam 208 from the plungers of switches 205, 206 and 201 thereby openingthe solenoid control lines I95, I90 and I9I. However, the three solenoidcontrol lines are provided with three branch control circuits 2I I, 2I2and 2I3 which contain normally open switches 2I4, 2I5 and 2l6respectively. As isbest shown in Figure 16, the switches 2I5 and 2I6,which are also of the plunger type, are adapted to be operated by a pairof cams 2H and 2| 8, respectively, which are likewise fixed. to theshaft 209. Switch 2I4 is adapted to be operated by a cam 2I9 carried bya sleeve 220 which is freely rotatable upon the shaft 209 and carries asecond operating lever 22L As is best shown in Figures 17 through 20,when the main control handle 204 is shifted to the dotted line positionof 2I0 in Figure 17, the automatic control mechanism for thetransmissions is disconnected at switches 205, 206 and 201 but branchlines 2, 2I2 and 2I3 remain open at their switches 2 I4, 2 I 5 and 2 I5.This provides a low gear ratio for hoisting purposes, because all of thetransmission control valve solenoids are de-energized. Likewise duringdrilling operations, when the handle 204 is in the dotted line positionof 2I0, the rotary table drive is at its, Movement of the handle 204high speed ratio. to the position indicated by dotted line 222 in Figure17 causes cam 2I8 to close switch 2I5' thereby actuating the controlvalve I84 and shift.- ing transmission 5! to its high speed ratio for.hoisting purposes. Since switches 2M and 2I6 remain open, this positionprovides the second gear for hoisting purposes and an intermediate orsecond gear for driving the rotary table. Movement of the control handle204 to the dotted line position 223 causes cam 2I8 to close switch 2 I0, while cam 2 I8 retains switch 215 in its closed position. This placestransmissions 5| and 53 in their high gear ratios for hoisting purposes,thus providing the third gear for hoisting and a low gear for drivingthe rotary table.

As previously indicated, the cam 2I9 which controls switch 2I4 is notfixed to the shaft 20.9: but is carried by the sleeve 220. However, aring 224 fixed to shaft 209 alongside of the cam 2I9 is provided with adog 225, which on clockwise movement of the control handle 204 from. thesolid line position of Figure 17 to the dotted line position 2I0, ismoved into contact with an abutment face 226 on the cam 2 I9 withoutmoving the cam. Thereafter, as the handle 204 is progressively moved ina counterclockwise di-,, rection, as viewed in Figure 1'7, cam 2I9'willmove in the same direction as cams 2|I and H8. When the handle 204reaches the dotted line position 223 previously mentioned thus closingswitches 2I5 and 2| 6, switch 2I4 will still remain open. However, ifthe handle 204 is shifted into the dotted line position 221, the cam 2I9will close switch 2 I4 and place the entire transmission mechanism inits high gear ratio for hoisting purposes.

The lost motion connection between shaft 209 and cam 2I9 is provided inorder to permit adjustment of the speed ratio of transmission I4independently of the speed ratios of transmissions 5I and 53 so that thegear ratio to the slush pump may be controlled independently duringdrilling operations. Accordingly, during drilling, the gear ratio to therotary table may be shifted to anyone of the three available speedratios by shifting the handle 204 to anyone of the positions 2 I0, 222or 223 and with the control handle 204, in any one of such threepositions, handle 22I may be shifted to close or open switch 2 I4 asdesired and thus control the speed ratio of transmission I4. The handle22I may also be used to control the speed ratio of transmission I4during reverse table rotation.

As important advantage of the particular form of transmissionillustrated at I4 and described above is that the one way brake blocksautomatically prevent reverse rotation of the planet housing on shiftsof the transmission from one gear ratio to the other during hoisting.Consequently, it is not necessary to carefully time the engagement ofthe means for preventing such reverse rotation with the disengagement ofthe planet brakes as is required when brake bands and the like areemployed to hold the planet housing against rotation, as shown in connection with transmissions 5| and 53. This is an important considerationin hoisting operations since it eliminates the danger of momentarilydropping the load between the transmission shifts. However,transmissions 5| and 53 cannot be constructed in the same manner astransmission I4 for the reason that at different times during thedrilling operations, power is transmitted through them in differentdirections. Consequently, the mechanism for holding the planet cagesagainst rotation must prevent rotation in one direction under onecondition and in the opposite direction underv another condition. It isfor that reason that brake bands are employed in the transmissions 5Iand 53.

In order to avoid the disadvantages of the brake band construction,there is shown in Figure 24 an alternative form of transmission unitwhich may be employed in lieu of that disclosed at 5|. As shown partlyin diagrammatic manner in Figure 24, the transmission unit indicatedgenerally at 228 is identical to the transmission 5I except for themechanism employed to hold the planet cage 229 against rotation when thetransmission is in its 2 to 1 ratio. In place of the brake band employedin transmission 5|, transmission 228 is provided with three equallyspaced pairs of one way brake blocks, one pair of which the other of theblocks inoperative to produce the desired operating conditions.

This mechanism, which is mounted upon the closure plate 233 for therecess in the housing 232, comp-rises a double ended cylinder 234containing a pair of pistons 235 and 236 connected 7 by a rod 231. Aspring 238 normally holds the two pistons at the right-hand end of theirstroke, as viewed in Figure 24, and air pressure may be admitted throughline 239 to the right-hand end ofthe cylinder to shift both pistons tothe lefthand end of their stroke. A dog 249 fixed to the piston rod 231passes through a slot formed in the plate 233 and operates to shift oneor the otherv of blocks 23!] and 23! outwardly in the recess in such amanner as to prevent the block from wedging between the planet housingand the plate 233, as it must to prevent rotation of the housing.

The arrangement of the parts is such that the spring 238 normally holdsthe blocks 23l in an inoperative condition. Consequently, the planetcage may also rotate freely in counterclockwise direction, as viewed inFigure 24, but reverse or clockwise rotation is prevented by blocks 230.Accordingly, when the power is delivered to transmission 228 throughshaft 4| of Figure 1 for hoisting purposes, the transmission 228 willoperate in exactly the same manner as transmission I4, shifting from itshigh gear ratio of 1 to 1 to its low gear ratio of 2 to 1 when theplanet brakes are disengaged, and vice versa.

As previously indicated, the planet brakes are engaged by energizing thesolenoid I85 of control valve I84 and thus admitting air to the annularcylinder 15 of Figure 5. As shown diagrammatically in Figure 24, suchadmission of air under pressure to annular cylinder 15 will not normallyadmit air under pressure to cylinder 234 because of the provision of avalve 24! which normally blocks the flow of air under pressure to theline 239 and connects line 239 to the exhaust port 242. Valve 24l is asolenoid operated valve and its solenoid 243 may be energized by closinthe manually operated switch 244. Switch 244 is closed manually when itis desired to drive the rotary table in a forward direction. Suchclosure opens valve 24l and at the same time blocks its exhaust port242. Accordingly, when solenoid I85 is energized to open valve I84, airunder pressure will flow not only to the annular cylinder 15 but throughvalve 241 to the cylinder 234, thereby shifting the pistons 235 and 236to a position in which the dog 240 renders the one way brake block 230inoperative and permits the block 23| to return to its operativeposition. Consequently, the planet cage 229 is free to rotate in theclockwise direction, as viewed in Figure 24, as is required when it isin its 1 to 1 ratio and power is being delivered through it from shaft52 to shaft 4| of Figure 1. When it is desired to place transmission 228in its 2 to 1 ratio during forward table driving movement, solenoid I85is de-energized, thus connecting cylinders 234 and 15 to the exhaustport of valve I84, and permitting block 23l to hold the planet cage 229against counterclockwise rotation, as viewed in Figure 24.

A further advantage of the type of mechanism shown in Figure 24 over thebrake band mechanism of transmission is that by spacing the three pairsof blocks equally about the circumference of the planet cage, the cagemay be held against rotation without imposing any radial loads upon themain bearings of the transmission.

The construction shown in Figure 24 may also be employed in lieu oftransmission 53, previously described, provided the transmission is soinstalled that it provides a step-down speed ratio for hoisting purposesas distinguished from the previouslymentioned preferred reversearrangement of transmission 53.

As previously indicated, the differential switch control mechanism forthe transmission of the present invention is effective to maintain thetorque load on the hydrokinetic torque converter automatically withinsuch a range that the converter operates within a predetermined range ofspeed ratios independent of the speed of the converter input shaft. Insome cases, as where a governed engine is employed, or where for otherreasons the range of engine speeds is small, the same or comparableresults may be achieved without the use of the differential switchmechanisms by controlling the transmission shifting mechanism inaccordance with the speeds of the output shafts of each transmissionunit. An alternative construction of this type is illustrated more orless diagrammatically in Figures 22 and 23.

As shown in Figure 22, the complete power transmission system includesan engine 245, a hydrokinetic torque converter 246, and a two speedtransmission 241 which may be similar in construction to thetransmission I4 previously described. The output shaft 248 of thetransmission 241 has fixed thereto a sleeve 249 to which is pivoted anydesired number of equally spaced flyball governor arms 259, each of thearms being pivoted to the sleeve 249 by means of a pin 25I. Each of theflyball governor arms is provided with a roller 252 adapted to bearagainst the face of a ring 253 which is slidably mounted on the shaft248. The ring 253 is normally urged to the right of shaft 248 againstthe rollers 252 by means of a spring 254, which surrounds the shaft 248and which may be adjusted by means of a pair of lock nuts 255 and 256threaded on the shaft. An annular ring 251 surrounds a boss formed onthe ring 253 and is journaled for rotation on the ring 253 by means of apair of combined radial and axial thrust ball bearings, indicated at258. Fixed to the ring 257 in any suitable manner is a post 259 which isformed of insulating material and projects through a suitable slot 269formed on a stationary bracket 26l. An electrically conductive contactbar 262 is fixed to the post 259 and adapted to close an electricalcircuit between a pair of stationary contacts 263, which correspond tothe contacts I12 of Figure 15.

It will be apparent that the above described mechanism will be effectiveto close a circuit through contacts 263, and thus effect a shift of theassociated transmission 231 to its high gear ratio when the speed of theshaft 248 reaches a value at which centrifugal force acting on theflyball arms 250 overcomes the force exerted by the spring 254, and viceversa. It will also be apparent that any desired number of transmissionunits may be connected in series, each having a flyball governoroperated switch mechanism of the type shown in Figures 22 and 23 mountedon its output shaft. Thus, with three two-speed transmissions connectedin series, this type of shifting control mechanism will produce exactlythe same speed and torque characteristics shown on the foregoing tableprovided the engine speed remains constant, and provided the springs 254for each transmission control switch are so adjusted that the contactsclose at the respective transmission output shaft speeds indicated inthe table.

It will be apparent there is provided in accordance with the presentinvention an exceedingly compact rotary well drilling machine employinga hydrokinetic torque converter and an automatic transmission effectiveduring hoisting operations to maintain the torque converter within itsrange of maximum efficiency. As a result, for hoisting 25 purposes,extremelyflexible control of the hoisting speed at high eificiency maybe achieved by simply manipulating the throttle lever for the engines.This, combined with the high starting torque provided by thehydrokinetic torque converter, greatly reduces the time required for thesuccessive hoisting operations employed in removing the drill stemsection by section from the hole in order to change the drill bit. Inaddition, the mechanism is so constructed and arranged that by simplemanipulation of suitable clutch control levers, not shown, the sametransmission units employed in hoisting may be employed forindependently driving the rotary table and the slush pumps for drillingoperations.

While only two engines are employed in the form of inventionillustrated, it will be apparent that for larger units additionalengines may be connected to the shafts I and I2, if desired. It isunderstood that in such case, the output shafts of the additionalengines may either be directly connected to the input shafts of thetorque converters employed in connection with the engines 2 and 3, ormay be connected to the transmission through independent torqueconverters. In the latter case, it is preferred to employ a differentialthrottle control synchronizing mechanism of the type shown in Figures 6,7 and 8 for each additional engine in order to insure that the inputspeeds of all converters are the same speed during hoisting.

If desired, the slush pump power take-off can be omitted, in which eventtransmission unit I4 may either be omitted or it may be positioned inalignment with units and 53, with a resulting reduction in the over-allwidth of the machine. Any desired type of change speed transmission mayconnect shafts 4i and 54 or any number of the preferred form of twospeed transmission units may be employed. In addition, when the slushpump power take-on is omitted only one engine need be employed for lightdrilling operations.

While the invention is illustrated and described in connection with arotary well drilling machine, it will be apparent that many of theprinciples of the invention may be employed to advantage in other formsof hoisting apparatus or in any case where a wide range of torques andspeeds is required. In addition, the provision of a transmissionmechanism employing a plurality of stages connected in series throughone or more of which power may be delivered in either direction todifferent power take-offs, may also be used to advantage in any casewhere a single source of power is required to operate a plurality ofdifferent units either singly or in combination at diiferent times.Likewise the engine synchronizing mechanism by which the power deliveredby the engines is equalized may be employed in any case where aplurality of engines are utilized to drive through individualhydrokinetic torque transmitting devices, or their equivalent, a singleshaft or a pluruality of shafts whose speeds are mechanicallymaintainedat the same value.

While several modifications'of the mechanism are illustrated anddescribed, it will be apparent that others are available within thespirit of the invention and within the scope ,of the appended claims.Certain of the claims cover subject matter disclosed in applicantscopending applications, Serial No. 571,656, filed January 6, 1945 (nowabandoned), Serial No. 602,619, filed June 30, 1945, and Serial No.666,626, filed May 2, 1946.

What is claimed is:

l. A rotary power transmitting apparatus including a pair ofindependently operable change speed transmissions, three power take-offsconnected to said apparatus, two independent power input shafts,selectively operable means to connect both input shafts to one powertake-oil through both transmissions in succession, and selectivelyoperable means to connect one input shaft to the second power take-oil?through one transmission and to simultaneously connect the other inputshaft to the third power take-01f through the other transmission. 7

2. A rotary power transmitting apparatus including a pair ofindependently operable change speed transmissions connected in series toform a power transmitting mechanism, selectively operable means fordelivering power to either end of said mechanism, a pair of powertake-ofis connected to said mechanism intermediate said transmissions, aclutch operable to disconnect said mechanism intermediate said powertakeoifs, and a reversing gear train in said mechanism between one ofsaid power take-offs and the adjacent end of said mechanism.

3. A rotary power transmitting apparatus including a pair ofindependently operable change speed transmissions connected in series toform a power transmitting mechanism, selectively operable means fordelivering power to either end of said mechanism, a pair of powertake-offs connected to said mechanism intermediate said transmissions, athird power take-01f connected at one end of said mechanism, and aclutch operable to disconnect said mechanism intermediate said firstpair of power take-offs.

4. A rotary power transmitting apparatus including a pair ofindependently operable change speed transmissions connected in series toform a power transmitting mechanism, selectively operable means fordelivering power to either end of said mechanism, a pair of powertake-offs connected to said mechanism intermediate said transmissions, athird power take-off connected at one end of said mechanism, a clutchoperable to disconnect said mechanism intermediate said first pair ofpower take-offs, and a reversing gear train in said mechanism on theopposite side of one of said transmissions from said power takeofis.

5. A rotary power transmitting apparatus including a pair ofindependently operable change speed transmissions connected in series toform a power transmitting mechanism, a pair of independent means fordelivering power to said mechanism, means for selectively connectingboth of said power delivery means to one end of said mechanism or adifferent one of said power delivery means to each end, a pair of powertakeoffs connected to said mechanism intermediate its ends, and a clutchfor disconnecting. said mechanism intermediate said power take-offs.

6. A rotary power transmitting apparatus m cluding a pair ofindependently operable change speed transmissions connected in series toform a power transmitting mechanism, a pair of independent means fordelivering power to said mechanism, means for selectively connectingboth of said power delivery means to one end of said mechanism or adifferent one of said power delivery means to each end, a pair of powertake offs connected to said mechanism intermediate said transmissions,and a clutch for disconnecting said mechanism intermediate said power"take-oifs.

7. A rotary power transmitting apparatus including a'pair ofindependently operable change speed transmissions connected in series toform a power transmitting mechanism, a pair of independent means fordelivering power to said mechanism, means for selectively connectingboth of said power delivery means to one end of said mechanism or adifferent one of said power delivery means to each end, a pair of powertakeofis connected to said mechanism intermediate its ends, a clutch fordisconnecting said mechanism intermediate said power take-ofis, and areversing gear train in said mechanism between one end thereof and theadjacent transmission.

8. A rotary power transmitting apparatus ineluding a pair ofindependently operable change speed transmissions connected in series toform a power transmitting mechanism, a pair of independent means fordelivering power to said mechanism, means for selectively connectingboth of said power delivery means to one end of said mechanism or adifferent one of said power de liver-y means to each end, a pair ofpower takeofis connected to said mechanism intermediate saidtransmissions, a clutch for disconnecting said mechanism intermediatesaid power takeofis, and a reversing gear train in said mechanismbetween one end thereof and the adjacent trans- I anism, means forselectively connecting both of said power delivery means to one end ofsaid mechanism or a different one of said power delivery means to eachend, a pair of power takeoifs connected to said mechanism intermediatesaid transmissions, a third power take-off connected to the mechanismbetween one end thereof and the adjacent transmission, and a clutch fordisconnecting said mechanism intermediate said first pair of powertake-offs.

10. A rotary power transmitting apparatus including a pair ofindependently operable change speed transmissions connected in series toform a power transmitting mechanism, a pair of independent means fordelivering power to said mechanism, means for selectively connectingboth of said power delivery means to one end of said mechanism or adifferent one of said power delivery means to each end, a pair of powertake-offs connected to said mechanism intermediate said transmissions, athird power take-off connected to the mechanism between one end thereofand the adjacent transmission, and a reversing gear train in saidmechanism between said one end thereof and said third power takeoff.

11. A rotary power transmitting apparatus comprising a pair of axiallyaligned shafts, a clutch for connecting said shafts, a second pair ofshafts, means including a disengageable clutch adapted to make a drivingconnection between one shaft of the first pair and a shaft of the otherpair, means including a disengageable clutch adapted to make a drivingconnection between the other shafts of said pairs, separate powertake-offs operatively associated with said second pair of shafts, meansincluding a change speed transmission connecting the second pair ofshafts, and separate means for delivering power to each shaft of thefirst pair. v

12. A rotary power transmitting apparatus comprising a pair of axiallyaligned shafts, a clutch for connecting said shafts, a second pair ofshafts, means including a disengageable clutch adapted to make a drivingconnection between one shaft of the first pair and a shaft of the otherpair, means including a disengageable clutch adapted to make a drivingconnection between the other shafts of said pairs, oneof said drivingconnections including reverse gearing, separate power take-offsoperatively associated with said second pair of shafts, means includinga change speed transmission connecting the second pair of shafts, andmeans for delivering power to one of the shafts of the first pair.

13. A rotary power transmitting apparatus comprising a pair of axiallyaligned shafts, a clutch for connecting said shafts, a second pair ofshafts, means including a disengageable clutch adapted to make a drivingconnection between one shaft of the first pair and a shaft of the otherpair, means including a disengageable clutch adapted to make a drivingconnection between the other shafts of said pairs, one of said drivingconnections including reverse gearing, separate power take-offsoperatively associated with said second pair of shafts, means includinga change speed transmission connecting the second pair of shafts,and'separate means for delivering power to each shaft.

CHARLES M. O'LEARY.

REFERENCES CITED The following references are of record in the file ofthis patent:

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